Numbers Don`t Say It All For Speakers

January 12, 1990|By Rich Warren.

The engineers from Infinity called to see how I liked their new loudspeaker, the RS 5 Kappa. I replied that the speakers certainly were not Phi Beta Kappa. In other words, they were good but not great.

This caused a great gnashing of teeth and intimations that my ears should be returned to the factory for service, because measurements show the speakers to have a wide, even frequency response. Indeed, Infinity rates the RS 5 Kappa from 49 hertz in the bass region to 45,000 hertz in the treble, with a variation between one end and the other of only 3 decibels, a most laudable achievement. (The last 25,000 hertz of that impressive figure is wasted, because the best human ears rarely if ever hear above 20,000 hertz.)

Specifications usually do not reveal the true nature of a loudspeaker. If you could decide upon a speaker simply by looking at numbers, there might be only a few dozen models from which to choose, rather than the thousands that exist. Furthermore, you could order them from a mail-order catalogue rather than visiting several audio stores to listen to different brands and models.

Infinity crafts a most attractive cabinet for the RS 5 Kappa. It rounds the front corners and carves vertical channels in the curve. Infinity claims that this visually pleasing ridged design aids in diffusing the sound coming from the speaker, a desirable effect. The well-made enclosure comes finished in high-quality oak veneer. The enclosure measures 17 by 10 1/2 by 9 1/2 inches. Infinity offers custom pedestals, as these speakers sound best when raised off the floor.

Inside the enclosure are a 6 1/2-inch injection-molded graphite woofer and Infinity`s proprietary EMIT (electromagnetic induction) tweeter. This tweeter-neither cone nor dome-uses an ultralow-mass flat diaphragm, which accounts for its extended high-frequency response. The woofer employs the latest in high-tech cone materials. Graphite combines the benefits of low mass and stiffness, without succumbing to uneven vibrations of the cone.

For all this care and wizardry, the RS 5 Kappa sounds merely good. The

``bright`` treble is unflattering. Infinity includes a tweeter level control to adjust this to personal taste; but even with the control turned one-third of the way down, the speaker retained an unpleasant edge. Human voices sound a bit harsh after extended listening, and the speakers tend to exaggerate the flaws of poorly recorded CDs.

Stereo imaging is good. The speakers provide a convincing illusion of instrumental and vocal placement.

Infinity rates the impedance of the RS 5 Kappa at 4 ohms. This means that they could tax a few receivers or amplifiers and that they should never be used simultaneously with another pair of speakers. The combined impedance, which would then fall well below 4 ohms, could damage many receivers or amplifiers. The RS 5 Kappas require a minimum of 20 watts of continuous power per channel. Infinity provides a useful, intelligent instruction manual with the speakers.

At a suggested retail price of $800 per pair, the RS 5 Kappas are the same price as the Mission Cyrus 782s. The Mission speakers offer better sound for the money, even if they reach only 20,000 hertz.

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Have a question about audio or video equipment? Address it to Rich Warren in care of Friday Audio-Video Section, The Chicago Tribune, 435 N. Michigan Ave., Chicago, Ill. 60611. Questions cannot be answered personally, but those of general interest will be answered in future columns.